An Ultrastructural Study of the Symbiotic Relationships of Four Strains of Bradyrhizobium Japonicum with Glycine Max PDF Download

Author: Mary Christine Huber
Publisher:
ISBN:
Category : Ultrastructure (Biology)
Languages : en
Pages : 1202

Get Book Here

Book Description
As much as 80% of the seed protein found in soybean seeds can be attributed to the nitrogen-fixing activity of the microsymbiont, Bradyrhizobium japonicum, that resides in root nodules of soybean. The effectiveness of this combination is limited, however, and the duration of nitrogen fixation lasts only about 3 weeks. B. japonicum infects soybean roots by inducing formation of infection threads and cortical cell division centers that will form nodule primordia. Once this organism reaches these centers, it infects the cells by the process of endocytosis. The microsymbiont resides within them in a specialized structure, known as a symbiosome. In this study I examined ultrastructurally and biochemically the development of this symbiotic relationship by infecting the soybean cultivar Williams 82 with four closely-related strains of B. japonicum. I report here that symbiotic effectiveness (persistence of nitrogen fixation) is dependent upon the ability of these microorganisms both to infect and persist within the root nodule. I also present evidence that ultrastructurally observable host defense responses are correlated with limited infection potential and the early decline of nitrogen fixation.